@mixin bg_image($url){
  background-image: url($url + "@2x.png");
  @media  (min-device-pixel-ratio: 3){
    background-image: url($url + "@3x.png");
  }
}

@mixin border-1px($color){
  position: relative;
  &:after{
    display: block;
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    border-top: 1px solid $color;
    content: ' ';
  }
  @media (-webkit-min-device-pixel-ratio: 1.5),(min-device-pixel-ratio: 1.5){
      &:after{
        -webkit-transform: scaleY(0.7);
        transform: scaleY(0.7);
      }
  }
  @media (-webkit-min-device-pixel-ratio: 2),(min-device-pixel-ratio: 2){
      &:after{
        -webkit-transform: scaleY(0.5);
        transform: scaleY(0.5);
      }
  }
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3){
      &:after{
        -webkit-transform: scaleY(0.334);
        transform: scaleY(0.334);
      }
  }
}
@mixin border-top-1px($color) {
  position: relative;
  &:before {
    display: block;
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    border-top: 1px solid $color;
    content: ' ';
  }
  @media (-webkit-min-device-pixel-ratio: 1.5), (min-device-pixel-ratio: 1.5) {
    &:before {
      -webkit-transform: scaleY(0.7);
      transform: scaleY(0.7);
    }
  }
  @media (-webkit-min-device-pixel-ratio: 2), (min-device-pixel-ratio: 2) {
    &:before {
      -webkit-transform: scaleY(0.5);
      transform: scaleY(0.5);
    }
  }
  @media (-webkit-min-device-pixel-ratio: 3), (min-device-pixel-ratio: 3) {
    &:before {
      -webkit-transform: scaleY(0.334);
      transform: scaleY(0.334);
    }
  }
}
